2,673 research outputs found
Exceptional contact damage tolerance of alumina-based multilayer ceramics with tailored microstructures
Simplicity - the key to fruitful medical research
Medical research is here divided -into two broad
categories. The great majority of research is "complex"
and includes all studies of intricate body mechanisms.
A minority of research is "simple" and deals mainly with
direct relationships between human environmental or lifestyle
factors and disease incidence (or with analogous
studies on animals). In addition, it includes studies
of simple body mechanisms. Examples are provided to
demonstrate that most of our medical knowledge of practical
benefit derives from simple research. This is particularly
the case in the area of prevention
D1-brane with Overcritical Electric Field in AdS3 and S-brane
We study aspects of Dirichlet S-branes, which are defined as Dirichlet
boundary condition on a time like embedding of open strings, in general
backgrounds. By applying T-duality along an isometry of the unphysical
dS2-branes in NS-NS supported AdS3-background, we find S0-brane. We also study
the time dependent tachyon condensation on the unstable Dp-brane and interpret
the singular solutions as lower dimensional S(p-1)-brane that couples to real
Ramond-Ramond fields while to imaginary NS-NS modes.Comment: 23 pages, JHEP style, V2: minor changes, typos fixe
On the Universal Tachyon and Geometrical Tachyon
We study properties of non-BPS D(p+1)-brane in the background of k
NS5-branes, with one transverse direction compactified on a circle, from the
point of view of Dirac-Born-Infeld action. We present the analysis of two
different embedding of non-BPS D(p+1)-brane in given background and study the
classical solutions of given world-volume theory. We argue for the
configuration of a non-BPS D(p+1)-brane which allows us to find solutions of
the equations of motion that give unified descriptions of G and U-type branes.Comment: 24 pages, minor change
An Intense Wave/Particle Event in the Auroral Ionosphere
An intense burst of VLF waves, at frequencies just above the local proton gyrofrequency, was observed shortly after each of two intense bursts of fieldâaligned suprathermal electrons (E \u3c 250eV) by instruments carried on a sounding rocket flown in diffuse aurora. If the two phenomena are associated with each other, the implication is that the electron acceleration occurred nearby, in a relatively small volume
Zeolite Synthesis under Insertion of Silica Rich Filtration Residues from Industrial Wastewater Reconditioning
Zeolite synthesis was studied using two silica rich filtration residues (FR 1 and FR 2) as Si-source and sodium aluminate in a direct synthesis at 60°C at strong alkaline conditions (8 M - 16 M NaOH). In addition to these one-pot syntheses, a two-step process was investigated. Here, an alkaline digestion of FR at 60°C was followed by gel precipitation with sodium aluminate and gel crystallization under usual conditions of 80°C - 90°C. The results show that the substitution of chemical reagent sodium silicate by a waste material like FR as Si-source is possible but requires fine tuning of the reaction conditions as zeolite crystallization is a process under kinetic control. The solubility behaviour and impurities of the inserted filtration residues strongly influenced the course of reaction. Thus zeolites like hydrosodalite or intermediate zeolite between cancrinite and sodalite, or zeolite NaA or Z-21 in cocrystallization with hydrosodalite could be observed in the one pot syntheses already in a short time interval between 1 - 4 h depending on the alkalinity. The two step process yield to zeolites NaA and NaX in very good quality. The reaction process of FR in both reaction methods was characterized by chemical analyses, X-ray powder diffraction, Fourier transform infrared spectroscopy as well as scanning electron microscopy. Surface area and water content of selected products were further characterized by the BET-method and by thermogravimetry. Summing up the results, we can show that zeolite formation from filtration residues is possible by several reaction procedures as model cases for a re-use of industrial waste materials. Beside the importance for environmental protection, the reactions are of interest for zeolite chemistry as the re-use of FR is possible under economically conditions of low energy consumption at 60°C and short reaction periods.DF
Note on D-Brane Effective Action in the Linear Dilaton Background
In this short note we will study effective action for unstable D-brane in
linear dilaton background. We will solve the equation of motion for large T and
we will calculate the stress energy tensor. Then we compare our results with
the calculations performed using exact conformal field theory description of
the open string worldsheet theory.Comment: 12 page
Spatial and temporal variation of ultrafine particles in the Bavarian centres of the NAKO health study: Augsburg and Regensburg
Reaction of Ph2C(X)(CO2H) (X = OH, NH2) with [VO(OR)3] (R = Et, nPr): Structure, magnetic susceptibility and ROP capability
Reaction of [VO(OR)3] (R = Et, nPr) with 2,2âČ-diphenylglycine afforded the alkoxide-bridged dimers {[VO(OR)(ÎŒ-OR)][Ph2C(NH2)(CO2)]}2, whereas use of benzilic acid, in the presence of alkali metals, afforded 16-membered metallocycles {V8(O)4M(OR)8[Ph2C(OH)(CO2)]12} (M = <1 Na, K). For the ring systems, magnetic susceptibility data is consistent with mixed-valence vanadium with an average oxidation state of 3.5. The dimer and ring systems are capable of the ring opening polymerisation (ROP) of Ï”-caprolactone under N2, air, or as melts affording mostly low to medium molecular weight cyclic and linear products
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